Portable safety lamp



Nov. 22, 1955 Filed July 6, 1954 D. D. DENN|s 2,724,752

PORTABLE SAFETY LAMP 2 Sheets-Sheet 1 llllll D 'T/gw@ one I .DerwllsI@jmd Attar-nej Nov. 22, 1955 D. D. DENNIS PORTABLE SAFETY LAMP 2Sheets-Sheet 2 Filed July 6, 1954 55 /NVEH TOR United States PatentOiiice 2,724,752 Patented Nov. 22, 1955 PORTABLE SAFETY LAMP Donald D.Dennis, Indianapolis, Ind., assigner to Denley f Corporation,Indianapolis, Ind., a corporation of lndiana Application `luly 6,1954,.Serial No. 441,58()

9 Claims. (Cl. Zilli- 117) This invention relates to a fuse device forpreventing overheating of electrically operated units, such as inmotors, electric lamps, and in general in any device wherein there is anelectrical circuit which may under certain conditions causeva generationof an undue amount of heat, which undue amount may become serious eitherto the unit itself or tend to start combustion of surrounding materials.The invention is herein described in the one particular form as embodiedinl a portable lamp such as is usually carried about on the end of anextension cor-d. Lamps suspended from such cords generate considerableheat, and' particularly where those lamps are enclosed in a safety domev.used to `protect the lamp itself. There have been fires started byreason of the use .of such a portable lamp where the lamp has been lefthanging in a grain bin in an elevator, and then `the lamp beingforgotten, the 'bin is .filled with grainA to such a depth that `thelamp is covered over while still burning.

lt is the primary purpose of my invention to break the electricalcircuit to a device which may become unduly heated so as to set up aheated atmosphere therearound beyond the `kindling temperature of thesurrounding materials.

In addition Vto that general over-all purpose, there is the purpose .ofproviding an exceedingly simple but most effective structure toaccomplish the breaking of the electrical circuit in a very positive andcertain manner so that the circuit willwbe broken beyond any doubt whena certain temperature is reached in the zone wherein the fusingstructure is located.

A still further important object of the invention resides in the factthat fuse links may be q uite readily replaced after breaking under theiniiuence of the heat above a predetermined temperature, coupled withthe fact that the fuse element itself cannot be removed before suchfusing without mechanical injury tothe device.

A still further important object of the invention is to provide astructure wherein the fuse elements will break the circuit regardless ofin what position the device carr'ying `the fuse elements may bepositioned, such for example'in reference to a portable lamp, whether ornot the jlamp is `suspended to hang downwardly, is hung up to extendvertically, or is allowed to lie upon its side.

4These and many other objects and advantages of the invention willbecome apparent to those versed in the att-in the following descriptionof the invention as illustrateti -in the one particular form in theaccompanying drawings, vin which 'Fig. `l is a view in side elevationand partial section of a-portable-lamp structure embodying theinvention;

Fig. 2 is a transverse section on the line 2-2 in Fig. 1 n anenlargedscale;

Fig. 3 isa view in top plan of the lamp base and carrier;

Fig. 4 is a view in end elevation of a fuse holding bracket;

-Fig. '5 is a view in top plan of a fuse element;

Fig. 6 is a view in side elevation and partial section of the fuseassembly unit;

Fig. 7/is a view in bottom plan of the fuse assembly;

Fig. 8 is a modified form of circuit breaker and circuit maker in topplan View; and

Fig. 9 is a view in end elevation.

A. base 10 Vmade out of rubber in the usual manner carries a lamp socket11 from which there flares outwardly a dome base 12 whichscrew-threadedly engages a lamp cover dome 13`. The usual incandescentlamp 14 is l,screw-threaded into the receptacle 11 before the dome 13 isengaged with the base 12. This much of the structure is standard andwell known. The invention is provided in an assembly which is applied tothis structure by mounting it inside otthe dome 13 and fixingy it to thefloor 15 of the base 1,2. outside of the socket 11'. The assembly isgenerally designated by the numeral 16. In this assembly there is a baseannular plate 17 made out of any suitable insulating material having ayhigh dielectric strength. A reector annular plate 18 preferably madeout of metal and having a high degree of heat and light reflection ismounted concentrically of the plates. 17 and spaced a .distancethereabove. In order to achieve the spacing between the plates, there isprovided a plurality of spacing posts 19, having a screw 20 enteredthrough the plates 18 and screw-threadedly engaged in the. upper end ofthe post 19, Fig. 6 in each instance. An insulating sleeve 21 snuglysurrounds the post 19 over its major length- -between the plates 18 and17 and then` a lower screw 22 is entered through a spacer thimble 23 toscrewthreadedly engage in the lower end of the post 19. lWashers 24 and25 are placed on the `opposite sides of the plates 18 between the post19 and sleeve 2.1 on the one side and the plates 17 and the spacer 23 onthe other side. There are four of these spacing devices employed inv thestructure as illustrated.

There is a plurality of brackets 26 mounted around the plates' 17, thebrackets 26 being mounted in pairs such as 27Vand 28, one on each sideof a post 19 and spaced circumferentially therefrom at equal distances.Each bracket 26 s rockably mounted by any suitable means, herein shownas by a rivet 29 extending through a foot 30 and down through the plate17. The foot 30 is preferably rockable about the rivet 29.

Referring toFig. 4, each bracket 26 has the mounting foot 430 from whichthe bracket extends by a leg I3.1 at right angles and upwardly to anupper bend 32 from which the vmetal of the bracket extends downwardlythrough a length 33 in intimate contact with the leg 31, down to a lowerbend 34. From the lower bend 34a leg extends upwardly parallel to thelegs 31 and 33, but in spaced relation therefrom. This leg 35 extendsupwardly to a top bend 36 at approximately the same elevation as thebend 32 and then there is a very short foot 37 turned downwardly betweenthe leg 35 and the leg 33. This leaves in effect a slot through thebracket between the legs 3'3 and 35, and between the lower end of thefoot 37 and the bend 34.

A spring 38 interconnects by its ends with a bracket 27 on one side anda bracket 28 on `the other side between adjacent posts 19, the spring 38tending to pull the two brackets 27 and 28 apart. There are threeofthese springs 38 arranged around the ring 17 between the correspondingbrackets, Fig. 2. A shorter spring 39 interengages the bracket 28 and asleeve 40 of insulating material which sleeve 40 in turn interengages orinterconnects with the next bracket 27.

A fuse link1 Fig. 5, is made outrof two strips of metal 42 and 43 ineifect soldered one to the other in overlapping end relation by asuitable fuse material. The material will vary in its make-up dependingupon the degree at which it is supposed to melt. Each of the strips 42and 43 normally tixed one to the other as just indicated has an end leg44 and 45 respectively turned in the same direction. One of these fuselinks generally designated by the numeral 46 is interengaged in eachpair of brackets 27, 23 by being slipped downwardly between the legs 32and 36 by end portions until the bends 42 and 43 slip past the foot 37to allow that foot to spring back into Contact with the upper portion ofthe leg 33 so that the fuse then cannot be lifted upwardly anddisengaged from the brackets. Also the legs 44 and 45 are positioned onthe outer edges of the brackets so that the fuse element 46 as a wholemay not slip longiand disengaged from the brackets. Also the legs 44 andin each pair cannot spread apart one from the other circumferentiallyaround the plate 17. On the other hand, the springs 3S and 39 tend topull the adjacent brackets one toward the other so as to hold them infirm abutment with the legs 44 and 45 of the individual fuses. In oherwords, each fuse 46 is held under tension by reason of the springs 38and 39.

Referring to Fig. 7, adjacent pairs of the brackets are interconnectedelectrically across the underside of the plate 17 by means of the busbars 47 interengaging the rivets 29. ri`hat is, these bus bars 47 serveas conductors between the pairs of brackets instead of the springs 38.inasmuch as the insulator sleeve interrupts the circuit between thebrackets 27 and 28 interconnected therethrough with the spring 39, leads48 and 49 are provided to extend inwardly from the rivets 29 of thosetwo adjacent brackets 26. One of these leads 4S extends to the centralterminal Sill in the socket l1, and the other lead 49 is in series withone of the wires coming through the cable 5t to the socket 11 so thatthe entire series of brackets and fuse links are electricallyinterconnected with the lamp 14 in series arrangement.

All of the fuse links 46 are freely confined between the lower and upperplates t7 and 18 so that they are not normally in direct line ofwave-travel from the heat source of the lamp I4. The upper plate I8 issubstantially of the same internal and external diameters as those ofthe lower plate 17. The assembly carrying the fuse links 46 is mountedon the iioor 1S by allowing the screw heads 22 to rest on that floor andthere are a plurality of screws 53 passing through the lower plate 17and scre.vthreadedly engaging the member 12, Fig. 1.

The structure described is substantially moisture and dust tight inrespect to the lamp 14 and the fuse assembly. Normally there is a wireguard fixed to the member 12 around the groove 54, but not herein shownsince it is a standard element and does not enter into the inventron perse.

Assuming that the lamp i4 is energized, and that it is left burning andbecomes covered over with dust or other material until heat builds upwithin the dome 13 to that temperature at which the fusing materialbetween the members 42 and 43 will melt, heat from the lamp I4 will havebeen reected and diffused in effect from direct radiation on the fuses46, so that it is really the ambient temperature within the dome 13which controls. The reflector plate 18 operates to intercept heatdirectly radiating from the lamp 14 to prevent the straight lineradiation from reaching the fuses 46, so that it is the temperature ofthe air within the dome 13 which constitutes the ambient temperatureabout the fuses 46, rather than the directly radiated heat. When thatcritical temperature is reached, and the two members 42 and 43 arereleased one from the other by the melting of the intervening fusematerial, the springs 38 on either side of the brackets 27 and 28 whichcarry that particular released element will cause those brackets toquickly rock to the positions as indicated in the dash lines, Fig. 2,whereupon the fuse members 42 and 43 will likewise be rocked until theyare practically parallel under the pull of those springs. That is, whenthe fuse material melts, there is initially a wiping and pulling apartaction of the members 42 and 43 in CII respect one to the other, so thatthere is a clean break between the members causing a positiveinterruption of the circuit. Any one or all of the links may release atthe same time depending upon the characteristics of the fuse material,the slight variations there may have been in the over-all structure, butmore particularly depending upon the position of the lamp 14 whether itbe vertically positioned upwardly or downwardly or extendinghorizontally or inclined. In any event, regardless of the position ofthe lamp t4, there will be at least one of the fuse members 46 releasedat the critical temperature for which the fuse material has beenselected.

As indicated in Figs. 8 and 9, the fuse device may be employed not onlyto break a circuit, but in adidtion to breaking a circuit, to completinga second or third circuit as may be desired. In this modied form, a pairof the brackets 27 and 28 are rockably mounted on a base 5S to swingaround their rivets 29. A fuse link 46 is inserted across and into thesebrackets 27 and 2S, and the springs 38 tend to pull apart those brackets27 and 28 to the positions at least as indicated by the dash lines. Whenthe fuse 46 is subjected to an ambient temperature which causes thefusing metal to let loose between the members 42 and 43, the springs 38will kick the brackets 27 and 28 around to those dash line positions andcarry the fuse elements 42 and 43 against fixed brackets 56 and 57 whichhave the upturned legs 58 and 59. Since the brackets 56 and 57 are iixedin position on the member 55, they will effectively stop both of thefuse elements 42 and 43 in those dash line positions as shown in Fig. 8.Normally there would be a circuit completed between the brackets 27 and2S, and when the fuse element 46 is separated, then selectively, acircuit may be completed between one of the brackets such as bracket 27and a stop bracket 56, or another circuit between the bracket 28 and thebracket 57 completed, either selectively or both circuits at the sametime as may be desired. In this manner, not only is the primary circuitinterrupted between the brackets 27 and 28, but also a second circuitmay be completed between the brackets 27 and the bracket 56 to somesuitable alarm or indicating device (not shown) and likewise anothersignaling circuit or other device operating circuit may be completedbetween the brackets 28 and 57 through those fuse members 42 and 43respectively.

Therefore, while I have described my invention in the one particularform, it is obvious that structural changes may be employed withoutdeparting from the spirit of the invention, and I therefore do notdesire to be limited to that precise form beyond the limitations whichmay be imposed by the following claims.

I claim:

l. A fuse structure protecting against a predetermined rise in ambienttemperature from a heat source, comprising a base member, a plurality ofpairs of brackets rockably mounted around the member with axes in agenerally circumferential line; a heat separable fuse linkinterconnecting the brackets in each pair; means interengaging the linksand the brackets limiting swinging of the brackets one from the other ineach pair; a spring normally under tension interconnecting a bracket ofone pair with the next adjacent bracket of the next adjacent pairmaintaining said links under tension; and insulating means interposedbetween one of said springs and a bracket interrupting an electricalcircuit through the brackets and fuses.

2. The structure of claim l in which said brackets each have a slotthereacross, and each link is inserted by end portions across the slots,said link carried means comprising legs turned from the ends of thelinks to abut the outer sides of the brackets preventing travel of thebracket from the link.

3. The structure of claim l in which each link is in two parts withcentral overlapping end portions adhered one face thereof against theother through an intervening fuse material, the fuse material beinglimited in area to the area of the overlapping of said parts.

4. The structure of claim l in which there is a heat reflector anddiffuser plate mounted in spaced relation between said links and saidheat source.

5. The structure of claim 4 in which said reflector is mounted on saidbase member with said links in spaced relation between the reector andthe base member.

6. The structure of claim 5 in which said base member is a ring and saidretiector is also a ring wherein said links are confined within thecircumferential boundaries thereof.

7. A circuit breaker structure comprising a base member; a pair ofspaced apart brackets carried by said base rockably mounted onsubstantially parallel axes; a fuse link engaging both of said brackets;spring means normally tending to rock apart said brackets; said fuselink normally holding said brackets against rocking under action of saidspring means; said fuse link being separable upon a predeterminedambient temperature being reached to release said brackets from beingheld by the link; said fuse link comprising two relatively rigid membersoverlapping by end portions between said brackets; and a metal meltingat said predetermined temperature below the melting point of saidmembers, said metal normally interengaging said end portions.

8. A circuit breaker structure comprising a base member; a pair ofspaced apart brackets carried by said base rockably mounted onsubstantially parallel axes; a fuse link engaging both of said brackets;spring means normally tending to rock apart said brackets; said fuselink normally holding said brackets against rocking under action of saidspring means; said fuse link being separable upon a predeterminedambient temperature being reached to release said brackets from beingheld by the link; a terminal post iixedly carried by said base in thepath of and abutted by one of said end portions when said membersseparate under action of said spring means rocking its carrying bracket,whereby a second circuit may be closed between said carrying bracket andsaid terminal.

9. A circuit breaker structure comprising a base member; a pair ofspaced apart brackets carried by said base rockably mounted onsubstantially parallel axes; a fuse link engaging both of said brackets;spring means normally tending to rock apart said brackets; said fuselink normally holding said brackets against rocking under action of saidspring means; said fuse link being separable upon a predeterminedambient temperature being reached to release said brackets from beingheld by the link; an external heat source producing said ambienttemperature; a heat reilector member carried in spaced relation betweenand intercepting direct radiation from said heat source and extendingover said fuse link; and said reflector member being opened beyond saidextent and providing free access therearound between said source andsaid fuse link for conducted and convected heat from said source to saidlink, such conducted and convected heat setting up said ambienttemperature.

References Cited in the iile of this patent UNITED STATES PATENTS465,046 McLain Dec. 15, 1891 601,492 Blackwell Mar. 29, 1898 726,605Wilson Apr. 28, 1903 850,334 Anderson et al Apr. 16, 1907 982,281Lincoln et al Ian. 24, 1911 1,734,230 Roe Nov. 5, 1929 1,934,244Steinmayer Nov. 7, 1933 2,071,067 Gizzarelli Feb. 16, 1937 2,538,574Kolisch Ian. 16, 1951 FOREIGN PATENTS 325,285 Great Britain Feb. 17,1930

